Good day everybody.

I am trying to calculate the proportion of one of the survey variables, over a specific variable
that woyld be like:
svy: prop perm3, over (pain)
but now, I want to have this calculation in a specific age (not for all of the observations)
So, I tried to do this:
svy: prop perm3, over (pain), if (age < 12)
.
Apparently this is not true and I can't add "if" to the end of this code, when I am using svy prefix. (It gives an answer, but it's wrong)

I've read the svy manual, but didn't find any solution.
Any idea to help with this issue?

Thank you in advance